Apparatus for annealing extremely fine wires with steam

ABSTRACT

An apparatus for annealing extremely fine wires with steam wherein there is provided an annealing tube penetrating the heating chamber of an annealing furnace provided with an electrical heater; into the outlet side of the annealing tube is slidably inserted a cooling tube so as to have the length of its outward extending portion varied; the interspace between both tubes is sealed at said outlet end; the interspace between both tubes and the cooling tube are filled with steam introduced from the outlet side of the annealing tube; under this condition, an extremely fine copper wire is made to travel from the inlet of the annealing tube to the outlet of the cooling tube, thereby providing a very fine bright annealed wire with a clean surface which is sufficiently soft to afford good workability.

United States Patent [1 1 11 3,721,431

Nishida 51March 20, 1973 [54] APPARATUS FOR ANNEALING EXTREMELY FINE WIRES WITH Primary Examiner-Gerald A. Dost STEAM Attorney-Flynn & Frishauf [75] Inventor: Tokutaro Nlshida, Ashikaga-shr, ABSTRACT Tochlgi-ken, Japan An apparatus for annealing extremely fine wires with [73] Asslgnce: Nlppon Semen Cable Tokyo steam wherein there is provided an annealing tube Japan penetrating the heating chamber of an annealing fur- [22] Filed: Sept. 22, 1971 nace provided with an electrical heater; into the outlet [2 Appl No: 182,617 side of the annealing tube is slida bly inserted a cooling tube so as to have the length of its outward extending portion varied; the interspace between both tubes is [52] U.S. Cl. R, 148/132 ealed at aid outlet end; the inte space between both Int. Cl. -.C21d tubes and the cooling tube are team in- [58] Field of Search ..266/3 R; 148/132 troduced f the outlet Side f the annealing tube; under this condition, an extremely fine copper wire is I [56] References Cited made to travel from the inlet of the annealing tube to UNITED STATES PATENTS the outlet of the cooling tu be, thereby providing a very fine bright annealed wire with a clean surface 1,905,810 4/1933 Cowan et al ..l48/l3.2 which is sufficiently soft to afford good workability.

3,126,301 3/1964 Faler ..266/3 R 3,182,982 5/1965 Ruff ..266/3 R 1 Claim, 1 Drawing Figure APPARATUS FOR ANNEALING EXTREMELY FINE WIRES WITH STEAM BACKGROUND OF THE INVENTION This invention relates to an apparatus for continuously performing the bright annealing of extremely fine wires in an atmosphere of steam heated to high temperatures.

Extremely fine drawn wires.

Where they are to be worked, for example into a coil in the enameled form, there appears a phenomenon of backward spring, obstructing their winding. It is therefore necessary that hard drawn copper wires should be annealed into a soft type before they are coated with enamel. On the other hand, the copper wire is annealed at high temperatures as several hundred degrees of centigrade. If, therefore, exposed to air under such extremely heated condition, the wire will have its surface instantly oxidized. To avoid this oxidation, bright annealing should be conducted in an atmosphere of inert gas. There have heretofore been used various kinds of inert gas. However, these gases have the drawbacks that not only they are expensive, but also gaseous impurities, for example, minute amounts of H 8 and NI-I contained therein are likely to corrode the surface of the copper wire. Accordingly, it is advantageous to use steam to prevent said oxidation or corrosion.

Annealing apparatuses using steam known to date include a type wherein there is disposed, for example, an inclined annealing tube in an annealing furnace, the lower end of said tube being immersed in the water. According to this apparatus, there is inserted a hard copper wire from the upper end of the annealing tube open to the air the hard copper wire softened by annealing is conducted from the lower outlet of the annealing tube through a guide wheel disposed in the water to the succeeding enamel coating step. The hot soft copper wire is cooled when it enters the water sealing the lower end of the annealing tube, and at this time there is generated steam, which fills up the annealing tube to drive away air remaining therein. Accordingly, the soft copper wire can be subjected to bright annealing without being oxidized when heated.

This prior art annealing apparatus does not raise problems where a copper wire to be annealed is relatively thick, but can not be used with extremely fine wires having a diameter of, for example, 10 to 40 microns. With this apparatus, the cooling water sealing the lower end of the annealing tube is deposited on the surface of the copper wire. Upon evaporation of the deposited water, inorganic materials dissolved therein are retained on said surface. Even after the wire is coated with enamel, the retained inorganic materials are affected by atmospheric moisture, leading to the eventual corrosion of the surface of the copper wire. With a thick wire, the corrosion stops at its surface, whereas with an extremely fine wire, the corrosion extends there through, resulting in its breakage several months after its preparation. If there should occur the breakage of fine wires used in an electronic apparatus after its assembly, then there would be consumed a great deal of time in locating the cause of its failure. It may be contemplated inconnection with the prior art apparatus to wipe off cooling water deposited on extremely fine wires. However, this will impart a tension to said wires with the resultant elongation, sometimes giving rise to their breakage. Said tension also takes place in the wires when they pass through the cooling water and are conducted by the water-immersed guide wheel, similarly leading to their elongation or breakage.

According to anoyher conventional annealing apparatus using steam, the annealing tube placed in the annealing furnace is disposed horizontal and the outlet of said tube is sealed with, for example, a piece of cloth or felt. Into the annealing tube is introduced steam produced by a separate steam generator, and there is always allowed cooling water to flow through said seal material.

Also with this latter type of known annealing apparatus using a horizontal annealing tube, the cooling water attaches itself to the surface of the object wire when it is drawn through the seal material as in the former apparatus. Since the seal material directly contacts a hot annealed wire, it is appreciably worn, with the result that scraps of the seal material sometimes deposit on the surface of the wire. Further, since the annealed wire is extremely fine, the seal material has to be taken out of the annealing apparatus each time the wire is rnade to pass there through, this operation being accompanied with considerable difii culties.

SUMMARY or THE INVENTION It is accordingly the object of this invention to provide an apparatus for annealing extremely fine wires with steam which eliminates the drawbacks encountered with the prior art apparatuses for annealing such wires in an atmosphere of steam and produces bright annealed extremely fine wires sufficiently soft for good workability and having a clear surface.

This object is attained by the annealing apparatus of the present invention comprising an annealing furnace consisting of a heating chamber enclosed with heat insulating material, an electric heater disposed in said heating chamber, and an annealing tube passing through said heating chamber with its inlet and outlet made to communicate with the outside of the heating chamber and means for introducing steam into the annealing tube, characterized in that a cooling tube through which to conduct an extremely fine wire is disposed in the annealing tube so as to slide there through in its axial direction with one end of said cooling tube extending outward from the outlet side of the annealing tube; and of the annealing tube there is introduced steam from the neighborhood of the outlet through the interspace between the annealing tube and cooling tube so as to be filled thereinto.

BRIEF DESCRIPTION OF THE DRAWING The appended drawing is a sectional view of an apparatus for annealing extremely fine wires with steam according to an embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION Feferring to the drawing, there is defined by the inner walls of a metal casing l a heating or annealing chamber 3 surrounded with heat insulating material 2. In the annealing chamber 3 is disposed an electric heater 5 supported by a support member 4 made of insulating material. The annealing chamber 3 is heated to a temperature of several hundred degrees of centigrade. An annealing tube 6 made of, for example, metal which is to be heated by the electrical heater passes through the heat insulating material 2. Thus is constructed an annealing furnace 7 according to this invention. Into the outlet end 8 of the annealing tube 6 is inserted a cooling tube 9 made of, for example, metal. The interspace between the annealing tube 6 and cooling tube 9 is sealed with seal material 10, for example, fluorine resin tape in such a manner that the cooling tube 9 may be so supported to slide back and forth through the annealing tube 6 as indicated by the arrows A. Accordingly, the cooling tube 9 enables its portion extending outward from the outlet end 8 of the annealing tube 6 to be freely vaied in lengh. That portion of the wall of the annealing tube 6 which is disposed near its outlet end 8 is bored on one side with a hole 1 1, which communicates with a steam generator (not shown) through a steam pipe 12 and valve 13 so as to conduct steam into the annealing tube 6. In the apparatus of this invention for continuously annealing extremely fine wires with steam, an extremely narrow drawn wire, for example, to 40 microns in diameter is continuously conducted into the annealing tube 6 from its inlet end 15, then through the cooling tube 9 and further from its outlet 16 to an enamel coating device (not shown) by means of a wire feeder (not shown).

There will now be described the operation of the indicated opparatus of this invention. When the valve 13 is opened, steam is supplied through the pipe 12 to be filled into the annealing tube 6 through the hole 11. When, under this condition, electric current is introduced through the heater 5 and the extremely fine copper wire 14 is made to travel, then part of the steam present in the annealing tube 6 is also brought into the cooling tube 9 by being carried with the wire 14, thereby substantially expelling air from the interior of the annealing tube 6 and cooling tube 9, and preventing the wire 14 from being oxidized even when heated in the annealing furnace 7. The wire 14 which has been drawn to a desired very small thickness is conducted in the hardened state into the annealing tube 6 from its inlet 15 and annealed into a soft type by being heated to a temperature of about 400 C in the annealing chamber 3. The wire 14 thus softened is gradually cooled while passing through the cooling tube 9 and taken out of the annealing apparatus at the outlet 16 of the cooling tube 9 without being oxidized in a state cooled to a temperature slightly higher than the dew point of steam, for example, about 150 C. The temperature of the wire 14 at the outlet 16 of the cooling tube 9 is determined by the length of that part thereof extending outside of the annealing tube 6, the travelling speed of the wire 14 and the temperature of the steam supplied through the hole 11. In practical application, however, it is convenient to define said temperature by varying the length of the outward extending portion of the cooling tube 9. If the temperature of the wire 14 at the cooling tube outlet 16 is so controlled as to stand at a higher level than the dew point of steam, that is, at least over C, then the annealed wire 14 will be taken out of said outlet 16 without being oxidized and having its surface contaminated with the deposition of water droplets, thus attaininfig1 bri ht annealinfi. This bright annealing was success lly e ected by a owmg the outlet portion of the cooling tube 9 to extend 40 mm outside of the annealing tube 6, where said annealing tube 6 was 10 mm in inner diameter and 1,200 mm long, said cooling tube 9 was 4 mm in inner diameter and 500 mm long and an extremely fine wire 14 30 to 40 microns indiameter was made to travel at the rate of 150 m/min, and also by choosing the length of said outward extending portion of the cooling tube 9 to be 20 mm where an extremely fine wire 14 13 to 15 microns in diameter was conducted at the rate of m/min.

The wire 14 thus annealed has its surface kept free from the deposition of water droplets, realizes bright annealing without touching a seal material and in consequence is protected from breakage due to corrosion. Accordingly, the wire 14 can be manufactured in extremely good yield despite its very fine thickness. Further, the wire which has thus been fully annealed is very soft and substantially relieved of elasticity, so that where the wire is to be used as a coil for a very compact electronic apparatus such as an electronic watch, it can be shaped into a very accurate form free from the occurence of backward spring. The extremely fine wire prepared by the apparatus of this invention is particularly adapted to be worked into an angular coil having a very small curvature.

What is claimed is:

1. An apparatus for annealing extremely fine wires with steam which comprises an annealing furnace consisting of heating chamber, surrounded with heat insulating material, an electric heater disposed in said heating chamber and an annealing tube passing through said heating chamber and having its inlet and outlet made to communicate with the outside thereof; a cooling tube so sealed as to slide through the annealing tube in its axial direction with one end portion of said cooling tube extending outside of the outlet of said annealing tube; and means for conducting steam from the neighborhood of the outlet of said annealing tube through the interspace between said annealing tube and cooling tube to fill up both tubes. 

1. An apparatus for annealing extremely fine wires with steam which comprises an annealing furnace consisting of heating chamber, surrounded with heat insulating material, an electric heater disposed in said heating chamber and an annealing tube passing through said heating chamber and having its inlet and outlet made to communicate with the outside thereof; a cooling tube so sealed as to slide through the annealing tube in its axial direction with one end portion of said cooling tube extending outside of the outlet of said annealing tube; and means for conducting steam from the neighborhood of the outlet of said annealing tube through the interspace between said annealing tube and cooling tube to fill up both tubes. 